Fernando Vergara, File, Associated Press
In this Aug. 15, 2012 file photo, police patrol in a coca field as hired farmers uproot coca shrubs as part of a manual eradication campaign of illegal crops in San Miguel on Colombia's southern border with Ecuador. An annual U.N. report released on Wednesday, July 15, 2015 says Colombia has surpassed Peru in land under coca cultivation, the plant used to make cocaine.

LIMA, Peru — Colombia surpassed Peru last year in land under coca cultivation, with Peru experiencing a 14 percent drop in acreage for the plant used to make cocaine, according to U.N. data released Wednesday.

The U.N. Office on Drugs and Crime's annual report on Peruvian coca's crop said it encompassed 42,900 hectares (67 square miles). It's the crop's fourth straight year of decline and smallest area under cultivation since 1998.

That does not necessarily mean that Colombia is now the world's No. 1 cocaine producer, however. Much of Peru's crop is more mature and higher yielding, having never been subjected to eradication.

Peru does not destroy coca in the Apurimac, Ene and Mantaro river valley, the world' leading coca-growing region, citing security concerns. The size of Belgium and Israel combined, the valley accounts for 68 percent of Peru's coca crop.

Last year, President Ollanta Humala suspended U.S-backed plans to begin eradication there, and replaced the Peruvian drug czar who was advocating it.

The U.S. Office of National Drug Control Policy estimates Peru's potential cocaine production for 2014 at 285 metric tons versus 245 metric tons for Colombia. Neither Peru nor the U.N. compile estimates on potential cocaine production for Peru.

Two weeks ago, the U.N. said Colombia's coca acreage skyrocketed in 2014 from 48,000 hectares to 69,000 hectares (75 square miles to 108 square miles). That's in large part because of reduced aerial spraying. The herbicide used, glyphosate, was recently classified by a U.N. health agency as a probable carcinogen.

Peru only eradicates manually.

"We are the Andean region country that has advanced most in reducing coca leaf," Peruvian drug czar Alberto Otarola told reporters. Peru destroyed 31,000 hectares of coca last year and has set the goal of destroying 35,000 hectares this year.

One potentially telling figure is the amount of coca leaf produced per country. In 2014, Peru produced 100,800 metric tons compared to 132,700 metric tons for Colombia, according to Flavio Mirella, the Peru country representative for the U.N. agency.

The vast majority of coca leaf grown in both countries is used to produce cocaine.

The U.N and the U.S. both agree that Bolivia is the No. 3 cocaine-producing nation after Colombia and Peru. The White House put its estimated potential cocaine production there last year at 210 metric tons, up from 145 metric tons in 2012.

Bolivia has become a major transit and refining country for Peruvian cocaine in the past few years.

The U.S. ended counter-narcotics assistance to Bolivia in 2013, five years after its government expelled the U.S. Drug Enforcement Administration.

Associated Press writer Franklin Briceno contributed to this report.